I am unable to create a world in single player mode (all multiplayer options disabled). By clicking "play" and "making new world", it is not possible to create a new world.
Later, I found out that I could create a world by taking the tablet offline, starting the game and during the time the game is logging in it is possbile to create a world. Once the logging on is completed, the option to create a world is disabled.
To me this is a bug, not a feature.
I'm also unable to do this on Xbox One for one of the Xbox Accounts. On mine I all of a sudden was unable to create worlds (only account on xbox). I deleted all of my worlds and then after that I was able to create worlds again. There wasn't anything crazy about the size of the worlds. All together, less than 2GB I would guess. No world was over a GB.
I then created an account for my son and he has been unable to create any more worlds after the first one he created.
I've uninstalled and reinstalled the game, but nothing improved.